CLASS TEST GRADE PHYSICAL SCIENCES: CHEMISTRY Test 4: Matter and materials MARKS: 45 TIME: hour INSTRUCTIONS AND INFORMATION. Answer ALL the questions. 2. You may use non-programmable calculators. 3. You may use appropriate mathematical instruments. 4. Number the answers correctly according to the numbering system used in this question paper. 5. Data sheets are attached for your use. 6. Wherever motivation, discussion, et cetera is required, write brief answers.
SECTION A QUESTION : ONE-WORD ANSWERS Give ONE word or term for EACH of the following descriptions. Write only the word or term next to the question number (..2).. The net electrostatic force that two atoms sharing electrons exert on each other. ().2 The measure of the average kinetic energy of the molecules. () [2] QUESTION 2: FALSE STATEMENTS Correct the following FALSE statements. Write the correct statement next to the question number (2. 2.2). 2. A p n junction diode has a high resistance to current flow when it is (2) 2.2 For a given mass of gas at constant pressure, volume is inversely proportional to temperature. (2) [4] QUESTION 3: MULTIPLE-CHOICE QUESTIONS Choose the correct answer to the following questions. Write only the letter (A D) next to the question number (3. 3.2). 3. Which one of the following elements is a semiconductor? A phosphorus B arsenic C antimony D germanium (2) 3.2 Two moles of argon gas is sealed in a 2 dm 3 container. Which one of the following will remain unchanged when the container is heated? A The pressure inside the container B Average kinetic energy of the molecules C The concentration of the gas D The number of collisions with the walls of the container (2) [4] TOTAL SECTION A: 0 Maskew Miller Longman, Focus on Physical Sciences Grade Test 4: Matter and materials Page 2 of 6
SECTION B INSTRUCTIONS AND INFORMATION. The formulae and substitutions must be shown in ALL calculations. 2. Round off your answers to TWO decimal places where applicable. QUESTION 4 4. What is doping? () 4.2 Describe two common methods of doping. In each case name the dopant. (4) 4.3 Describe what happens when a junction diode is forward-biased. (2) 4.4 Explain in terms of holes and electrons how current is conducted in a p-type semiconductor. (2) [9] QUESTION 5 The sketch below illustrates the changes in potential energy when two hydrogen atoms approach each other. A E p 0 B D Nuclear distance C Which point(s) on the sketch: 5. indicates where the molecule formed 5.2 represent the bond length 5.3 indicates repulsion between nuclei 5.4 indicates the most stable state 5.5 represents the ground state? [5] Maskew Miller Longman, Focus on Physical Sciences Grade Test 4: Matter and materials Page 3 of 6
QUESTION 6 6. Draw Lewis diagrams for: 6.. N 2 6..2 HOCl 6..3 H 2 S (3) 6.2 Use an example to explain what a dative covalent bond is. (3) 6.3 Write down the oxidation numbers of the underlined elements. 6.3. CO 6.3.2 H 2 SO 3 6.3.3 K 2 Cr 2 O 7 (3) [9] QUESTION 7 7. Write down the defining equation for Boyle s law. () 7.2 Name the two factors that must be constant when investigating Boyle s law. (2) 7.3 5,6 g of a diatomic gas occupies a volume of 3,00 0 3 m 3 at a temperature of 25 C and a pressure of 65 kpa. 7.3. Calculate the molar mass of the gas. (6) 7.3.2 Write down the name of the gas. (2) 7.3.3 What important assumption has been made in these calculations? () [2] TOTAL SECTION B: 35 GRAND TOTAL: 45 Maskew Miller Longman, Focus on Physical Sciences Grade Test 4: Matter and materials Page 4 of 6
DATA FOR PHYSICAL SCIENCES GRADE CHEMISTRY PHYSICAL CONSTANTS NAME SYMBOL VALUE Avogadro s constant N A 6,02 0 23 mol Molar gas constant R 8,3 J K mol Standard pressure p θ,03 0 5 Pa Molar gas volume at STP V m 22,4 dm 3 mol Standard temperature T θ 273 K FORMULAE p V T = p V 2 2 T pv = nrt 2 n = m M c = n V c = MV m n a nb = c V a a c b V b Printed with permission, National Department of Education Maskew Miller Longman, Focus on Physical Sciences Grade Test 4: Matter and materials Page 5 of 6
(I) H 3 Li 7 Na 23 9 K 39 37 Rb 86 55 Cs 33 87 Fr 2 (II) 4 Be 9 2 Mg 24 20 Ca 40 38 Sr 88 56 Ba 37 88 Ra 226 THE PERIODIC TABLE OF ELEMENTS 3 4 5 6 7 8 9 0 2 3 (III) 5 B 4 (IV) 5 (V) 6 (VI) 7 (VII) 8 (VIII) 2 He 4 0 Ne 20 8 Ar 40 36 Kr 84 54 Xe 3 86 Rn,0 2,,5 2,0 2,5 3,0 3,5 2,8 3,0 4,0 3 Al 6 C 2 4 Si 7 N 4 5 P 8 O 6 6 S 32 34 Se 9 F 9 7 Cl 35,5 35 Br 80 53 I 27 85 At 0,9,2,5,8 2, 2,5 2 Sc 45 39 22 Ti 27 3 28 32 Ge 73 50 Sn 3 33 As 75 5 Sb 0,8,0,3,5,6 48 40 23,6 V 5 4 24,5 Cr 52 42 25,8 Mn 55 43 26,8 Fe 56 44 27,8 Co 59 45 28,9 Ni 59 46 29,6 Cu 63,5 47 30,6,8 2,0 2,4 Y 89 57 Zr Zn 65 48 Ga 70 49 79 52 Te 28 84 Po 0,8,0,2,4,8,9 2,2 2,2 2,2,9,7,7,8,9 2, 2,5 2,5 La 39 89 9 72 Hf Nb 92 73 Mo 96 74 Tc Ru 0 76 Rh 03 77 Pd 06 78 Ag 08 79 Cd 2 80 In 5 8 9 82 Pb 207 22 83 Bi 209 0,7 0,9,6 79 Ta 8 W 84 75,8,8,9 2,0 KEY Atomic number Ac Re 86 29 Cu 63,5 Electronegativity Symbol Os 90 Ir 92 Pt 95 Au 97 Hg 20 Tl 204 58 Ce 40 59 Pr 4 60 Nd 44 6 Pm 62 Sm 50 63 Eu 52 64 Gd 57 65 Tb 59 66 Dy 63 90 Th 232 9 Pa 92 U 238 93 Np 94 Pu 95 Am 96 Cm Printed with permission, National Department of Education 97 Bk 98 67 Ho 65 99 Es 68 Er 67 00 69 Tm 69 0 Md 70 Yb 73 02 No 7 Lu 75 03 Lr 0,7 0,9,9 Approximate relative atomic mass Maskew Miller Longman, Focus on Physical Sciences Grade Test 4: Matter and materials Page 6 of 6